On October 17, 2017, our perception of interstellar travel changed forever. No, we did not discover an alien spaceship or a means of traveling faster than light, but something just as interesting showed up: our Solar System’s first interstellar asteroid.

What makes this floating hunk of rock so special? Well, it moves faster than any spacecraft in existence and, more terrifyingly, it isn’t alone.

From Beyond The Stars

When the Pan-STARRS 1 telescope in Hawaii first spotted this asteroid, it was not exactly sure what it was seeing. Its body was elongated and flat, similar to a gigantic frisbee. This odd shape led scientists to calculate the asteroid’s orbital trajectory, and the results were staggering.

The calculations revealed that this disc-shaped rock was undoubtedly from outside of our Solar System. Thrilled at finding our first interstellar asteroid, scientists gave it a name: Oumuamua.

Faster Than Anyone Imagined

“We had to act quickly,” said Olivier Hainaut, a scientist from ESO in Garching, Germany. The asteroid was moving much faster than they anticipated, which left them with little room to research it. “Oumuamua had already passed its closest point to the Sun and was heading back into interstellar space.”

Measuring in at an estimated 400 meters long, Oumuamua speeds along the galaxy at upwards of 95,000 kilometers per hour. Yet, despite its high speed, scientists estimate that the asteroid spent hundreds of millions of years traversing the Milky Way before entering our Solar System. Being the first interstellar asteroid we have witnessed, you would expect this to be rare – yet, you’d be wrong.

Not An Uncommon Occurrence

Upon further examination, scientists have hypothesized that Oumuamua is only one of many interstellar asteroids that have passed Earth throughout the years. In fact, they believe asteroids like Oumuamua pass through our Solar System about once per year.

So why did we not notice them until now? In the past, telescopes have not been nearly as advanced as they are today. With the invention of precise and powerful machines like the Pan-STARR 1, we can now see these invisible giants passing by our world.